Speed and distance indicating instrument



Aug. 6, 1940. E. L. VAIL SPEED AND DISTANCE INDICATING INSTRUMENT FiledJan. 14, 1937 ATTC'RNEY.

Patented Aug. 6, 1940 PATENT OFFICE SPE D Edgar L. Vail, New

Jaeger Watch Company, Inc., a corporation of New York AND DISTANCEINDICATING INSTRUMENT York, N. Y., assignor to New York, N. Y.,

Application January 14, 1937, Serial No. 120,53?

8Claims.

This invention relates to instruments for indicating speed and distance,and more particularly to an instrument'for use in aircraft or the likefor indicating speed and distance with respect to the surrounding airand with respect to ground.

Indicating instruments which are commonly used on aircraft, are capableof indicating only the speed of the craft and distance travelled withrespect to the surrounding air, or air speed and air distance. Sincesuch devices do not take into account the wind velocity, it is only bymental calculations that the pilot can determine the ground speed andthe total miles flown.

which indicates the actual distance flown as well as the air speed andthe true ground speed. Such a device, however, to be most useful to the7 pilot, must be so designed that the various scales are located in a.convenient position and are easily read and interpreted without thenecessity for any mathematical calculations.- Furthermore, anyadjustment mechanism must be simple and readily accessible inasmuch asthe adjustment must be effected by the pilot while in flight and atirregular periods in accordance with data received from the ground.

It is accordingly an object of the present invention to provide a novelinstrument of the above type which is simple and light in construction,convenient to adjust and read and dependable in operaton.

Another object is to provide such a novel instrument which may bereadily, set or adjusted to 35 compensate 'for difierent wind velocitiesso as to indicate the true ground speed and distance flown relative tothe ground.

Another object is to provide a novel instrument of the above type inwhich both the air speed and ground-speed are indicated onconcentrically located scales.

Another object is to provide an improved instrument of the above type inwhich both the ground speed indicating mechanism and the ground distanceindicating mechanism are adjusted by means of a single, easily actuatedcontrci.

Another-object is to providean instrument of the above type having meansto indicate both the air distance and the true ground distance or groundmiles flown. Various other objects will be apparent as the nature of theinvention is more fully disclosed.

A feature of the invention consistsin the provision, in an instrument ofthe above type, of a Hence, it is desirable to provide an instrument.

scale which may be shifted with respect to a pointer by an amountproportional to the wind velocity so that the corrected readingrepresents the true ground speed.

Another feature consists in the provision of two adjacent scales whichregister with the same pointer, one scale being stationary and beinggraduated to indicate the air speed and the other scale being adjustableand being graduated to indicate the ground speed. 7 2

Another feature consists in the provision of a wind velocity scale andan adjusting knob by which the movable scale may be easily adjusted tocompensate for various wind velocities.

Another feature consists in the provision of an odometer driven by atachometer through a variable speed gearing which is controlled inconjunction with the movable scale so as to indicate the true grounddistance travelled.

Another feature consists in provision of a single adjusting knob whichactuates both the adjustable scale and the variable speed device toefiect corresponding adjustments thereof whereby the adjustable scale iscaused to represent the ground speed and the odometer is caused toindicate the true ground miles flown.

Various other features consist in the combinations of parts and detailsof construction hereinafter more fully set forth.

In one embodiment of the invention the instrument comprises a standardmechanical or electrical tachometer driven by a propeller which ismounted on the vehicle in the outside medium as,

for example, on the strut of the aircraft or, in the case of a waterborne vessel is mounted in the surrounding water, in a position to bedriven at a speed proportional to the speed of the craft through themedium. The tachometer actuates a conventional speedometer mechanismequipped with a pointer which is movable over a scale to indicate theair speed and also drives an odometer which integrates the speed toindicate the total distance or mileage with respect to the air. Inaccordance with the present invention,

'a second scale is mounted concentric with the ,hereto, the broaderaspects of the invention will be better understood by referring to thefollowing description, taken in connection with the accompanyingdrawing, in which. one embodiment of the invention has been setforth forpurposes of illustration only.

In the drawing, Fig. 1 is a front elevation, partly in section, of anindicating instrument constructed in accordance with this invention;

Fig. 2 is a section taken on the line 2-2 of Fig.1 showing the positionof the adjusting knob and associated mechanism; and,

Fig. 3 is a section taken on the line 33 of Fig. 1 showing the variousdetails of construction.

Referring to the drawing more in detail, the instrument is shown ashaving a casing l provided with an outer peripheral flange H and acentral circular plate H! which is secured thereto by suitable means,such as screws, not shown. The plate I2 is provided at its peripherywith a scale l4 graduated to cooperate with a pointer 30 for indicatingair speed in suitable units, such as miles per hour. In the exampleshown, the scale I4 is graduated to read from zero to 300 miles per houralthough it is to be understood that various other designations may beemployed, depending upon the particular purpose of the instrument. Forindicating the ground speed, there is provided a movable ring l5; whichis adjustable about the periphery of the plate l2. As shown more indetail in Fig. 3, the ring may be provided with an inner flange it whichseats in a recess ll formed at the periphery of the plate l2. The

plate I2 is shown as formed by two discs l2a and l2b. which areseparated at their periphery to form the recess Ill. It is obvious,however, that other suitable constructions can be used to provide anarrangement such that the ring i5 is supported by and is slidable aroundthe periphery of the plate. Y

The ring I5 is provided with a scale having graduations similar to thescale is and being adapted to cooperate with the pointer for indicatingground speed in the manner to be pointed out. The outer periphery of thering' I5 maybe provided with a scale 2| which is graduated to read windvelocity and registers with an index point 22 formed on the outer flangeH of the casing. The scale 21 is graduated in both di-' rections from azero point so as to indicate the velocity of either ahead wind or tailwind, as will be described. It is to be understood that the scale 2! canbe formed on the stationary flange Ii instead of on the ring I5, ifdesired, index 22 then being formed on the ring l5.

For actuating the ring 15, there is provided a gear 22a carried upon ashaft 23 which is provided with an operating handle, such as a knurledknob 26, in a readily accessible position at the front of the casing.The gear 22a meshes with a rack 25 formed on the outer periphery of thering l5 and extending a sufiicient distance around the ring to providefor the desired movement thereof. The flange I l is provided with anarcuate recess 26 which provides clearance for the rack 25 and forms astop to engage the rack when pinned to said shaft.

thering l5 reaches its extreme positions so as to limit the movementthereof.

For actuating the pointer 30, there is provided suitable mechanismresponsive to speed of movement through the surrounding medium. In theembodiment shown this mechanism comprises a propeller 3| which ispositioned in the surrounding medium, as, for example, on the strut ofthe aircraft, and is connected by suitable remote control mechanism to astandard tachometer 32 which may be either of the mechanical orelectrical types and includes a mechanism, not shown, for driving ashaft 33 at a speed proportional to the speed of rotation of thepropeller 3|. This shaft 33 drives a standard speedometer mechanism 34(Fig. 1) through a gear train shown as an idler gear 35 and a gear 36meshing therewith and carried by the shaft 33. The speedometer mechanism34 is adapted to cause a deflection of the pointer 30 which isproportional to the speed of rotation of the driving mechanism and,consequently, proportional to the speed of movement of the craft throughthe surrounding medium.

For integrating the air distance flown, there is provided an odometer 40of standard construction and driven by a gear 4| meshing with a worm 42mounted on the shaft 33, the gear ratio being such that the odometerregisters the distance flown in suitable units, such as in miles. The

odometer 30 is supported by a suitable means,

such as a bracket 43, carried by the casing I0, and is visible throughan aperture 44 formedin the plate l2.

For indicating the ground miles, or distance travelled with respect toground, there is provided a second odometer which is supported by abracket 5| mounted on the casing I0 and is visible through a suitableaperture, not shown, in the plate l2. This second odometer 50 is drivenfrom the shaft 33 by a gear train including a var- .iable speed device.In the embodiment shown,

riphery of a friction disc 57. The friction disc 5? drives a frictionwheel 58 driving a second friction disc 59 which is mounted upon theshaft 60 of .the odometer 50 and causes actuation of said odometer. Thedisc 51 is'mounted on' a bracket 6! and may beheld in frictionalengagement with the wheel 58' by a spring 62 which is adapted topreventslippage and to compensate for wear'of the parts. I

In order to permit control of the variable speed mechanism to compensatefor the wind velocity, the friction wheel 58 is mounted for rotationupon a shaft 65 between collars 66 which are The shaft 65 is threaded ina rotatable bushing 61 journalled in a bracket 68 and is keyed for axialmovement in a bracket 59 by means of a key-way 70. A spring H, seatedaround the shaft 65 between the bracket 69 and a collar 12 formed onsaid shaft, tends to hold the shaft in a given set position and 'toeliminate lost motion.

The bushing 67 is provided with a bevelled gear 15 meshing with a secondbevelled gear 16 carried upon a shaft 11 which. is mounted in,a brackeet 18. The shaft 11 carries a worm wheel 79 meshing with a worm gear 80formed on or secured change the ratio between the speeds'of said discs.

In the operation of the above described embodiment, the ring 15 isadjusted manually in accordance with the scale 2| and the index mark 22to compensate for the wind velocity. In the position shown in Fig. 1,the scale 2| is set to indicate zero wind velocity. It is evident,however, that it will be shifted clockwise or counter-clockwise by anamount dependent upon the speed and direction of the wind, which data isobtained from the ground at regular intervals by the pilot.- When thering I5 is thus adjusted, the pointer 30 indi-' cates the air speed onthe scale l4 and the ground speed on the scale 20. Both of theseindications are readily observable at the same time by the pilot.Consequently, he has accurate knowledge of both the air and groundspeeds without making any mental calculations.

At the same time, the odometer 4B, which is driven by the shaft 33 inaccordance with the number of revolutions of the propeller 3|, indicatesthe miles flown with respect to the surrounding air.

The setting of the ring 15 by manipulation of the knob 24 also causeslongitudinal movement of the friction wheel 58 through the mechanismabove described and thereby varies the speed ratio between the odometer50 and the odometer 4B. The ratio of the various gears is such that thischange in speed of the odometer 50 compensates for the wind velocity.Consequently, the odometer 50 is made to indicate the actual groundmiles flown. The pilot thus has available an indication of the actualdistance covered as well as the air and ground'speeds and the air milesflown; This distance indication is particularly useful, for example, inblind flying and shows the pilot, without the necessity of mentalcalculations, when he has covered the proper distance to reach hisdestination.

It will be noted that the construction abovedescribed provides a simpleand dependable indicating instrument which makes the various readingssimultaneously available to thepilot. Furthermore, the adjustment issimple and can be readily efi'ected in night in accordance with changesin the known wind velocity. The same adjustment actuates both the groundspeed scale and the ground mile odometer and can be made withoutappreciably diverting the pilots attention from his other'duties.Obviously, one or more of these indications may be omitted if aknowledge of all of the above factors is not required in any particularcase. For example, if only theground distance indication is desired. theair distance odometer maybe omitted, or, if only the air speed isdesired, the ground speed scale may be omitted.

Although a particular embodiment of the invention has been shown forpurposes of illustration. it is to be expressly understood that theinvention is capable of various uses and that various changes andmodifications may be made therein as will be apparent to a personskilled in the art.

The instrument has been described, for simplicity,

as applied to an aircraft. It is evident. however, that it is alsoapplicable towater-borne ves 7 sels and the claims are to'be interpretedaccordingly. The invention is only to be limited in accordance with thefollowing claims when interpreted in view .of the prior art.

What is claimed is: 1. In an instrument for indicating speed anddistance of movement of a body in a medium which is movable with respectto the ground, a member driven at a speed proportional to the speed ofmovement of said body through said medium, speed indicating mechanismcomprising a pointer actuated by said member, a stationary scalecooperating therewith to indicate speed of movement through said medium,an adjustable scale also cooperating with said pointer and means foradjusting the position of said last scale to compensate for the knownvelocity of said medium so as to cause said last scale to indicate trueground speed, whereby both the speed in said medium and the ground speedare shown by the position of said pointer, integrating mechanism drivenby said member to indicate distance travelled through the medium andmeans actuated by said scale adjusting means to adjust the speed ratiobetween said member and said integrating mechanism to compensate for thevelocity of said medium so as to cause said last mechanism to indicatethe true ground distance travelled.

2. In an instrument for indicating speed and distance of movement of abody in a medium which is movable with respect to the ground, a memberdriven at a speed proportional to the speedof movement of said bodythrough said medium, speed indicating mechanism comprising a pointeractuated by said member, a stationary scale cooperating therewith toindicate speed of movement through said medium, an adjustable scale alsocooperating with said pointer and means for adjusting the position oisaid last scale to compensate for the known velocity of said medium soas to cause said last scale to indicate true ground speed, whereby boththe speed in said medium and the ground speed are shown by the positionof said pointer, a pair of integrating mechanisms driven by said member,one of said integrating mechanisms being adapted to indicate distancetravelled through said medium and means controlled by said adjustingmeans to adjust the speed ratio mtweenfsaid member and the other oi saidintegrating mechanisms so as to cause the latter to indicate true grounddistance travelled.

3. In an instrument for indicating speed and distance of movement of abody in a medium which is movable with respect to the ground, a memberdriven at a speed proportional to the speed oi movement of said bodythrough said medium, speed indicating mechanism comprising a pointeractuated by said member, an, adjustable scale cooperating therewith toindicate speed of movement, a scale representing velocity of said mediumassociated with said first scale, manual means to adjust said adjustablescale to compensate for the known velocity 0'! said medium so as tocause the same to indicate true ground speed, integrating mechanism toindicate distance, a variable speed device coupling said integratingmechanism in driven relationship to said member, and means associatedwith said manual means to adjust said variable speed device tocompensate for the known velocity of said medium so as to cause saidintegrating device to indicate true ground distance travelled.

'4. In an instrument for indicating speed and distance of movement of abody in amedium which is movable with respect to the ground, a rotordriven by movement through said meto rotation of said shaft, fixed andadjustable scales registering with said pointer to indicate respectivelyspeed in said medium and ground speed, a pair of integrating devicesdriven by said shaft to indicat distance, and meansadjusting the speedof one of said devices to compensate for the velocity of said mediumwhereby said devices indicate respectively distance 6. An instrument foruse in aircraft comprising, in combination, mechanism including apointer and a scale to indicate air speed, a second scale associatedwith said mechanism, manual: means to adjust the position of said secondscale to compensate for wind velocity, whereby said second scaletogether with said pointer is caused to indicate ground speed, anodometer driven with said indicating mechanism to indicate distance andmeans actuated by said manual means to vary the speed ratio of saidodometer with 'speeds, a pair of integrating devices driven at diiierentspeed to indicate respectively corrected and uncorrected distancestravelled, a single means for actuating said pointer and saidintegrating devices, and means for simultaneously controlling theposition of one of said scales and the speed of one of said integratingdevices.

8. In an instrument for indicating speed and distance of movement of a'body in 'a medium which is movable with respect to'the ground, a memberdriven at a speed proportional to the speed of movement of said bodythrough said medium, speed indicating mechanism actuated by said member,integratingmechanism driven by said member to indicate distancetravelled through the medium, and a single means to adjust said speedindicating mechanism and the speed ratio between said integratingmechanism and said member to compensate for the velocity of said mediumwith respect to the ground whereby said integrating mechanism is causedto indicate the true ground distance travelled and said speed indicatingmechanism is caused to indicate the true velocity of travel. I

' EDGAR L. VAIL.

